Ladies hosiery of improved stretch properties made from bifilament yarns

ABSTRACT

Textile garments such as ladies&#39;&#39; hosiery and panty hose have improved stretch characteristics when knitted from bifilament yarns possessing a figure-eight-type cross section comprised of two prominent lobes connected by concave side portions of uniform symmetry. The particular geometry of these bifilaments causes preferential alignment at yarn crossing points whereby a random amount of twist is imparted to a knitted construction and entrapped between loop sections forming the network of the garments to enhance their stretch characteristics as compared to garments prepared from yarns having differently shaped cross sections.

United States Patent Inventors James'MacDonaldJr.

Columbia, S.C.; Thomas F. Ballentine, Hopewell; Orvill E. Snider, Petersburg, Va.

App]. No. 733,491

Filed May 31, 1968 Patented Aug. 31, 1971 Assignee Allied Chemical Corporation New York, N.Y.

LADIES HOSIERY 0F IMPROVED STRETCH PROPERTIES MADE FROM BIFILAMENT YARNS 1 Claim, 20 Drawing Figs.

US. Cl 66/202 Int. Cl D04b 1/16 Field of Search 66 /202;

References Cited UNITED STATES PATENTS 2,988,420 6/1961 Ryan et a1 264/168 8/1968 Olson, 161/173 4/1950 Henley 15/159 UX 2,831,748 4/1958 264/177 X 2,945,739 7/1960 Lehmicke 264/177 3,109,220. 11/1963 McKinney et a1 57/140 X 3,156,607 11/1964 Strachan 66/202 X 3,162,995 12/1964 Comer et al. 57/140 X 3,315,021 4/1967 Luzzatto 264/177 X 3,308,221 3/1967 Opfell 214/177 Primary Examiner-Ronald Feldbaum Att0rneys- Francis W. Guay and Roy H, Massengill ABSTRACT: Textile garments such as ladies hosiery and panty hose have improved stretch characteristics when knitted from bifilament yarns possessing a figure-eight-type cross section comprised of two prominent lobes connected by concave side portions of uniform symmetry. The particular geometry of these bifilaments causes preferential alignment at yarn crossing points whereby a random amount of twist is imparted to a knitted construction and entrapped between loop sections forming the network of the garments to enhance their stretch characteristics as compared to garments prepared from yarns having differently shaped cross sections,

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LADIES nosiE'r iv oF IMPROVED STRETCH PROPERTIES MADE FROM BIFILAMENT'YARNS BACKGROUND or THE INVENTION Generally, ladies stretch hosiery have been made by falsetwisting round or triangular cross section yarn to provide the necessary elasticity. More recently, bicomponent yarns where one component is a homopolymer and the other component is a copolymer arranged either side-by-side or alternately with the homopolymer as a core in a sheath and core arrangement where the components have different shrinkage characteristics are employed. Such yarns while finding utility in ladies hosiery have a disadvantages in that three or more sizes are required to cover the range of 8% to 11% which is about 99 percent of ladies hosiery consumption in the United States. Additionally, various cross-sectional types such as trifilament, triangular, Y cross section, star cross section and the like have been employed to achieve decorative effects in these hosiery. in all cases three or more sizes are required to cover the range of hosiery requirements and generally the bursting and sagging in its normal course of wear.

It is also highly desirable to produce a stretch hosiery having adequate power of recovery to maintain a good fit without wrinkling or becoming permanently deformed under severe repetitive bending action such as deep-knee bends.

Prior art hosiery in the form of panty hose has insufficient stress power to avoid wrinkling and insufficient stress power to serve in the additional role of figure control. Thus, there has long been need to produce a stretch hosiery from a single homopolymer which avoids the described problems.

The evolutionary process has been taking .place over thousands of years for the development of natural fibers such eminently suitable for textile articles. In an attempt to simulate some of the geometric forms of natural fibers, there were configurations of bifilament yarn produced almost four decades ago from manmade cellulosic fibers ,as disclosed in Swiss Pat. No. 145,408 dated Feb. 28, 1931. Since this time several patents have issued showing various configurations representing a range of fiber types which have two or more lobes. For example, U.S. Pat. No.'3,156,607 dated Nov. 10, 1964 and US. Pat. No. 3,131,427 dated May 5, I964 demonstrate yarn configurations which are essentially bilobal. Thus, the prior art is replete with patents showing varioustypes of bilobal yarn, yet not a single patentee recognized the critical nature of the angle of intercept between the two lobes which is required to produce a high luster. and the elastic property essential to avoid the sagging of hosiery, particularly the elasticity sufficient to provide a good fit without the discomfort related to excessive force required to maintain the hosiery in position.

There has been another problem with prior art hosiery in that the stretch qualities on repetitive stretching of the hosiery results in continued loss of stress-strain properties.'Therefore, sagging and wrinkling of the hosiery may occur. While many suggestions have been offered to correct some of the forego ing problems, none appeared to be satisfactory in providing a hosiery which will fit the range of sizes of 8% to ll, provide sufficient sheerness over the indicated size range, and provide sufficient luster to be suitable for both office and for formal wear. Most particularly, hosiery produced thus far in the prior art has been quite deficient in elastic properties to provide a truly satisfactory fit over the range of sizes of 8% to l l.

With the foregoing discussion in mind, hosiery that exhibits the desired appearance in conjunction with the desired stretch SUMMARY OF THE INVENTION The product of this invention involves ladies hosiery and panty-hose-type garments of improved stretch characteristics containing bifilament yarns composed of prominent lobes having substantially circular peripheral surfaces connected together by concaveportions of uniform symmetry to form a figure-eight configuration. The bifilament yarns making up the network grid structure of the knitted products of this invention have prominent lobes fused together at an intercept angle of between 10 and 54. These lobed structures have a radius of curvature not greater than the radius of said concave portions. Because of the configuration of the bifilament yarns, when fashioned into the knit hosiery or panty hose, the broad concave areas of the bifilament yarns are aligned facing each other at stitch-crossing points. Since the major axis is characterized by convex portions of substantially equivalent symmetry to match the surface curvature or the concave portions, the alignment at yam-crossing points results in twist in the loops of the knit grid structure This self-imposed twist existing in each loop in multidirection imparts a high degree of elasticity to the knitted textile grid whereby the total elasticity of the textile grid or sections therein is a multiple of the amount of twist entrapped between each yarn-crossing point. This twist trapped in each loop of the knitted structures gives greatly increased multidirectional elasticity properties to the grid, since each twist in each loop, coarse and wale becomes a multiple of the total number of loops of the grid structure, thereby greatly enhancing its elasticity.

ln bright yarns, light reflects from each concave area presented to view in the loop areas as a minute point flash and alignment of each minute point flash results in a glace look," at a modification ratio of from 1.6 to 2.0 and a scintilla look" at a modification ratio of from (K/S2.05 to 3.0. Generally, false-twist bifilament yarns have a larger number of twists trapped in each loop than with yarns of other types of cross sections. As a result thereof a knitted structure made from such bifilaments has an enhanced overall luster. Thus, the bright bifilament yarns, textured and nontextured, when converted to plain knit-hosiery as an undyed boardered structure produce a luster value as follows:

Bright, nontextured8 to 41 (K/SXIOO) units;

Bright, false-twistl2 to 45 (l((S X) units.

These high luster values are due to alignment of minute point flashes in bright yarns. This uniform sheen or point scintilla has not thus far been obtained in prior art knitted structures.

In many cases it is desirable in hosiery to have a delustrant present such as Anatase TiO It has been found that the hosiery of this invention containing bifilament yarns which have at least 0.3 percent TiO have, clue to the opaqueness of the broad concave portions, between 50 and 100 percent greater covering power or hiding power as compared to round cross sections in identically constructed hosiery. Additionally, the undesirable chalkiness or greyishness which is characteristic of a round cross section, is decreased due to a slight The bifilament yarns are produced in accordance with a process described in copending applications, Ser. No. 733,556 and 733,557 filed on May 31, 1968. Thermoplastics in general can be employed for producing bifilament yarns which include the polyesters, polyamides, polycarbonates, polyureas, polyurethanes, polyphenylenes, polyoxymethylenes, polyolefins, polyacrylics, polyvinyl chlorides, and polypivalactones. Solvent spun materials may be employed such as polyacrylonitrile, but generally solution spun materials where water or solution is used as a quench material does not achieve a satisfactory circularity for the yarns of this invention.

Because of their excellent dyeing properties and good optical properties, polyamides usually are proposed for the production of bifilaments in accordance with this invention. Preferred polyamides are polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 6,6), and the polyamides made by the condensation of p,p'-bis(para-aminocyclohexyl)methane and dodecadioic acid to produce the polyamide poly[bis(para-aminocyclohexyl)methane dodecamide].

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section of spinnerette orifices employed to extrude the bifilament yarns employed in producing the hosiery with the present invention.

FIG. 1A is a cross-sectional view representing the bifilament yarns of this invention and further illustrating how the angular intercept is measured.

FIG. 2 illustrates graphically the relationships between the optical properties of the filament of the function of the angle of the bifilament intercept point versus the modification ratio.

FIG. 3 is a graph illustrating the luster of bifilament yarns employed in hosiery of this invention plotted against the modification ratio. The luster is reflected from the concave surfaces to give the unique observed sheen.

FIGS. 4 and 5 are photographs at 320 magnifications representing cross sections of undrawn bifilament yarns which have a modification ratio of 1.7 and 2.0, respectively, and which gives in hosiery form, the glace look.

FIGS. 6 and 7 are photographs at 560 and 900 magnifications of drawn bifilament yarns having a modification ratio of about 2.4 and 2.9, respectively. These yarns in hosiery forrn give the scintilla look."

FIG. 8 is a photograph illustrating the unique properties obtained when bifilament geometry is combined with a falsetwist operation and formed into hosiery. As may be observed, this illustrates the. alignment of the concave surfaces at stitch crossover points and the twist which is in the loop part exposes the broad part of the concave surfaces to view. This additionally illustrates the aligned rows of point light reflections from concave surfaces to give the unique sheen which can be observed. The magnification of FIGS. 8 through 13 is 36X..

FIG. 9 is a bifilament yarn in jersey knit hosiery which was not false-twisted. There is similar twist entrapment and alignment of light reflective areas as in FIG. 8, except to a lesser degree.

FIG. 10 is a photograph of a round cross-sectional yarn which is false-twisted and knit into hosiery. It can be observed that the light reflective areas are completely random, there is no twist between the stitches, and the yarn tends to curl back on itself rather than be twisted between the stitches.

FIG. 11 may be compared with FIG. 9 as false-twist photograph of round monofilament bicomponent plain knit hosiery. It also lacks the properties of twist entrapment and luster effect characteristics of the bifilament yarns.

FIG. 12 is a photograph of knit hosiery of false-twist round cross section, containing bicomponent filaments. Again, there is no alignment of the light areas in the yarn. Consequently, there is no luster or sheen, or enhancement of elasticity from twist entrapped between stitches.

FIG. 13 is a drawing of mesh hosiery (tuck stitch) made from trilobalor triangular-shaped yarns. As can be observed, the light reflective areas are random and significantly larger than those illustrated in FIGS. 8 and 9. Such yarns while suitable for many novelty end-uses have utility only as novelty yarns because of the garishness of the luster.

FIG. 14 is a photograph illustrating the force required to elongate bicomponent stretch yarn after one cycle of elongation and after six cycles of elongation. Stretch direction was lengthwise and the test sample was ladies hosiery with plain knit construction.

FIGS. 15 and 16 represent the same test parameters as for FIG. 14 except that FIG. 15 represents false-twist bifilament yarns of this invention which have superior elastic properties over that for F [G8, 14 and 16.

FIG. 16 represents false-twist round cross section nylon 6 yarn.

FIGS. 17, 18 and 19 represent, respectively, the properties of hosiery made from false-twist bifilament yarns, false-twist round filament yarns, and round cross section bicomponent sheath and core yarns. The nature of the test data illustrated in these figures is similar to that described for FIGS. 14, 15, and 16, except the measurement is in the transverse direction.

DESCRIPTION OF PREFERRED EMBODIMENT The bifilament yarns of the present invention, preferably, are prepared in accordance with copending applications of this same date, U.S. Ser. Nos. 733,556 and 733,557 filed on May 31, 1968 wherein a conventional extruder is employed to extrude polycaproamide through a spinneret of the type shown in FIG. 1. Typically to produce the glace look," the web separating orifices l and 3 in FIG. 1 should be between 0.5 and 3 mils, and to produce the scintilla look" or sparkletype yarns, the distance should be between 2% and 4 mils. This web may be interconnected by a distance not greater than 40 percent of the diameter of the orifices and it can be counterbored from the spinneret face for a distance of between 2 and 10 mils, provided this distance is not greater than 50 percent of the length of capillaries 1 and 3.

To produce ladies hosiery which have a glace look, it is essential that the lobes of the yarns making up the hosiery intercept at an angle of between 41 and 54. It is preferred that they have a modification ratio of between 1.60 and 2.5. At an intercept angle of greater than 54 insufficient luster is obtained and practically no twist entrapment is obtained between the filament loops of the knitted structures. To obtain the sparkle effect, the yarn making up this hosiery is in a figure-eight shape and the two prominent lobes are fused so that the concave sides intercept at an angle 6 ranging from 10 to 41, preferably at 16 to 38. The angle of intercept is determined by completing two circles outlined by filament lobes 12 and 14, then completing the line bisecting the center of the circles and the point where the circles of intercept are shown in FIG. 1A. The angle of intercept is the angle 19 between the horizontal line passing through the center and the line drawn to the intercept point. The modification ratio is determined by dividing the minimum width at the point of the upper and lower intercept point of the two circles into the length or the distance to the outer perimeter of the two circles. The relationship between the angle and the modification ratio is given in FIG. 2 wherein it is illustrated that as the modification ratio increases, the smaller is the angle of intercept.

The tip radius or circularity can be determined by ascertaining the total area of the circle of the lobes by measuring its total perimeter and then dividing this Development into the perimeter of a perfect circle enclosing the bifilament measured area. Generally, yarn contained in the hosiery of this invention will have a degree of circularity of greater than 0.9 but less than 1.2. A substantially larger deviation from circularity does not yield the same luster effects and those yarns with a circularity of substantially less than 0.9 cause difficulty in knitting because of tendency of these yarns to break out from backup of twist at the knitting needles.

The effects of modification ratio on the luster are illustrated in FIG. 3. Luster is ascertained by measuring light reflectivity with a Color-Eye" manufactured by The Instrument Development Laboratories, Attleboro, Massachusetts. The reflectivity is expressed by the Kubelka Munk equation where:

where R reflectivity ascertained with a color-eye of 55 7 millimicrons. The method for ascertaining the reflectance is described in Color and Business, Science & Industry" by D. B. Judd; John Wiley and Sons, New York, New York. As can be noted in FIG. 3, false-twist bifilament yarns have luster values quite significantly higher than nontextured bifilament yarns made in hosiery. This is due to greater quantity of twist entrapped between stitches and more concave reflecting points are present. Additionally, false-twist bifilament yarns in hosiery have somewhat subdued sparkle at any given point, even though the total luster is greater.

FIGS. 4 and 5 are photomicrographs at 320 magnifications of undrawn bifilament yarns having a modification ratio of 1.7 and 2.0, respectively. What is of particular significance is to note despite the random nature of the cross sections involved,

they tend to align with the convex surface fitting into the concave area and it is this alignment that yields marked elasticity in the hosiery grid structure due to entrapment of twist in the stitch. These yarns yield a glace look."

The yarn illustrated in FIGS. 6 and 7 yields the scintilla look, but as in FIGS. 4 and 5, there is a tendency for a random cross section to align with the convex portions fitting into the concave portions providing frictional contact which maintains twist entrapment in the loop section of the hosiery grid structure. Therefore, the bifilament yarns represented in FIGS. 4-7 are highly preferred for the present invention.

When these bifilament yarns are false-twisted and converted into a knitted structure a construction like that illustrated in FIG. 8 is formed. By critically examining photographs, it can be observed some loops are in focus and some loops are out of focus despite being at the same tension levels as employed to make the knit fabrics of FIGS. 10 and 12. It is this three-dimensionality which indicates latent stretch ability of the hosiery and renders it possible for one size to fit the majority of applications in ladies hosiery.

The yarn in FIG. 8 has 31 turns/inch twist imparted thereto, utilizing a Leesona 553 Superloft machine. It is knitted into hosiery using S and Z twist in alternate courses. It can be ob served from FIG. 8 that the light areas are short in length due to twist of the bifilament yarns between stitches; however, as can be noted, the light areas are all on an approximately similar plane. This results in a diaphanous luminous sheen which has been characterized as the glace look," and as the modification ratio of the bifilament yarns is increased, the length of the light flash increases. As the intensity thereof increases, each individual light colored point results in a scintillation point and the luminous sheen effect is replaced by a sparkle effect or the scintilla look. Between each stitch, it can be noted that the bifilament'yarn twists 90 first to present a flat plane to view over the course of the twist, at least another 180 for a total of at least 270, to present two concave planes to view. It is this twist superimposed upon the false-twist stretch that lends sufficient elasticity to the hosiery so that one size will span the range of sizes for most consumer end-uses. Additionally, as stitches in FIG. 8 are stretched, the twists trapped between the stitches in the manner stated above gradually untwist, and when tension is released, these twists rewind. After stretching, particularly in areas of hosiery where elongation ensues, that is, the areas which have great propensity to sag or wrinkle, the twist which has been unwound as the individual stitches are stretched out, rewind into a normal configuration and provide additional force superimposed on that from the false-twist crimp. Thus, the combined forces, at low elongations are adequate to hold a hosiery firm to the ankle or firm .to the knee without evidence of sagging or wrinkling. Moreover, such hosiery resists elongations after repetitive cycling.

The same bifilament yarns as discussed above but without false-twist are shown in the knit structure of FIG. 9 which illustrates that all light reflections are located at relatively precise points in the center of the plain knit stitch and along the sides of the stitch. Additionally, it can be noted that twist is entrapped between the stitches as in FIG. 8. Thus, hosiery containing bifilament yarns have improved elasticity and improved light reflectivity whether false-twisted or not.

Hosiery prepared from round cross section as in FIG. 11 have neither twist or luster. Hosiery of triangular cross section filaments in FIG. 13 present long broad light flashes, and are generally too garish, except for novelty end-uses. Additionally, hosiery made from this cross section, yarn as indicated in FIG. 13, have a reduction in stretch due to no-twist entrapment.

The hosiery of FIG. 8 may be compared with hosiery prepared from round cross section false-twist yarn (FIG. 10) and with bicomponent yarn (FIG. 12). Neither of these hosiery exhibits alignment of the light reflection areas or twist entrapment. In separate photographs not shown, triangular cross section yarn false-twisted shows only very slight twist entrapment, and long light flash areas similar to that illustrated in FIG. l3.

FIG. 15 illustrates the lengthwise extension versus stress strain load for hosiery constructed of the same yarn as that described for FIG. 8, e.g., false-twist bifilament yarn. As can be noted, the hose has a definite initial loading which is still quite high after six cycles of extension and which slopes upward at a substantially lower rate than the bicomponent round cross section yarn as illustrated in FIG. 14. Thus, it has a relatively uniform stretch characteristic maintaining a definite power after repetitive stretching sufficient to avoid wrinkling or sagging of the hosiery. It should be noted that in FIGS. 14 and 116, the bicomponent and round cross section yarns, after six cycles, have essentially lost their load capacity, particularly at 3 to 5 percent elongation. It is this loss of load capacity at low elongations which causes the hosiery to wrinkle and sag after several wearings.

The load capacity of these yarns in the transverse direction is demonstrated in FIGS. I7-ll9. Again, the round and bicomponent yarns represented in FIGS. 18 and 19 have zero load capacity at 3 percent elongation after six cycles whereas the bifilament yarn product has approximately 5 grams retractive force left under the same conditions.

When triangular or trilobal cross section yarn is converted into hosiery it exhibits similar properties to false-twist round cross section yarns in that very rapid loading occurs after 10 percent elongation and above. Thus, this rapid loading causes an uncomfortable effect on the part of the wearer as well as stresses individual filaments so as to increase the potential of runs or breakage of the filaments from sudden picks or impact.

The foregoing illustrative comparison made in connection with the drawings, demonstrates that, in general, luster of hosiery made from bifilament yarns is a function of the modification ratio whether it is a glace look or scintilla look." Hosiery made from round cross sections show quite different luster effects and do not demonstrate the glossy high-sheen or point sparkle effect characteristic of "the modification ratio of between 1.65 and 3.0 which is illustrated in FIGS. 2, 3, 4, and 5.

The bulk of ladies hosiery produced requires a low degree of transparency. To achieve this effect, Anatase TiO is dispersed in the monomer or at some point prior to completion of the polymerization cycle in the amount of 0.3 percent TiO- by weight of polymer for semidull articles and 2.0 percent by weight of TiO by weight of polymer for full-dull articles. This delustering quality is desirable for its hiding power; it has been found from panel jury ratings of the bifilament yarns of this invention that 50 to percent greater hiding power is achieved over round cross section yarns in equivalent hosiery structures. Additionally, hosiery made from the bifilament yarns of this invention have a slight reflective luster which tends to overcome undesirable chalkiness or greyishness exhibited when the yarn is made from converitional round cross section yarns.

The following examples further illustrate the invention.

EXAMPLES 1 THROUGH 14 5 Bifilament yarns employed in the manufacture of hosiery of this invention were prepared from polycaproamide pellets of 65 relative formic acid viscosity which were spun at a temperature of 265270 C. employing a conventional screw extruder for melting. Hosiery that had a glace look were prepared using a spinneret having twin orifices separated from each other for a distance of 2.0 mils and the hosiery which had a scintilla look" were prepared from yarns made by passing the polymer melt through twin orifices separated from each other for a distance of 3.0 mils.

The yarn was drawn at about 4.0 draw ratio and generally at a drawing speed of about 3,000 feet/min. Yarn which went into hosiery having stretch properties was placed on a Leesona 553 Superloft false-twisting machine and false-twisted to a 1 pound. Round and triangular cross section yarns were produced in a control manner in the same equipment and machinery.

These yams were knitted with a Textile Machine Works Mark IV 400-needle, 4 feed ladies circular knit hosiery machine, into medium length hosiery inches in length, after normal extension, and contained 2,100 courses throughout the full length thereof for an average of courses per inch. The polycaproarnide yarn was boarded at a temperature of 1 18 C. for the bifilament yarns and 108 C. for round cross 35 section yarns, both temperatures being the maximum suitable ti re ieq er. 9.125%??? l eches were?! to se 1 dyed hosiery placed over a standard leg form and the values are recorded as the average of observations from a panel jury of five experienced colorists. Observations were made under fluorescent light and bright daylight. Bright daylight assisted in showing the demarcation between the scintilla look and the glace look. These properties are defined in copending applications Ser. Nos. 733,556 and 733,557 filed on May 31, 1968.

It was noticed by the panel jury, that daylight emphasized sparkle. In table 1 is shown the evaluation of luster bifilament yarns wherein it can be observed that these lustered bifilament yarns have 50 to 100 percent more cover than was observed for hosiery comprised of round cross section yarns which were employed as the control. The actual visual rating for the increase in luster of false-twist bifilament yarn was compared with nontextured bifilament yarn in hosiery containing yarns having a modification ratio of greater than 2.1. The hosiery comprised of the false-twisted yarn has a luster between 150 and 200 percent greater'at equal extension on a standard' hosiery l'eg form.

The panel jury of experienced colorists rated the dyed 20 denier per filament bifilament yarns of this invention as having a sheer appearance value equivalent to 10 to 12 denier. This property is of significant value since it means that bifilament yarns have an improvement in sheerness value of about 150 percent and greater over hosiery prepared with round cross section yarns. This property is of significance since it means a sheer ry can be obtained without loss in wearing properties no 1y expected with the equivalent reduction in denier normally required in prior art hosiery to achieve equivalent sheerness values. Alternatively, a considerable improvement in sheerness appearance of the hosiery can be obtained at equal wearing properties to that obtained with normal hosiery. All luster values listed in table 1 were ascertained using Color-Eye fabric sample holder with a black background and TABLE l.OP.'1LC AL OR LUSTER PROPERTIES AS MEASURED ON THE BOARDED HOSIERY Percent Angle of luster Modifibifilament K/S by Ex. *1 cation intercept, Oolor- No. *2 Cross section ratio degree Eye" Panel jury *4 rating of the degree of silky sheen Glace Look" 1. 4 62 6. 0 No sheen, similar to round. 1 55 10.0 Good (A) subdued sheen *4. 1 40% greater cover compared with Example 6A.

Triangular *4 Good (B) "Glace Look with slight sparkle.

*5 Excellent point sparkle Scintilla Look".

*5 Good (B) heavy point sparkles.-

Low luster.

Dull without warmth.

Heavy sparkle, too garish for most end-uses in hosiery.

7A Br F-T Triangular Heavy Sparkle.

Br .do 1.9 46 18.0 *4 Good (B) Glace Look.

1. 8 49. 2 50% greater cover compared with Example 11. 2.8 17 40.0 *5 Excellent strong iridescent point sparkle Scintilla Look". l0 Br do 3.0 10 44.0 *5 Good (B) heavy point sparkle. 11 Br F-T Round 1.0 3.5 No luster. 12 Br F-T Bifilament... 2. 5 42 23.0 *5 Good (A).

Footnotes:

* FT= False twist; *1 SD Semidull hosiery; *2 Br= Bright hosiery. *3=Luster is measured on the white boarded hosiery before dyeing. *4, "5=The panel jury of 5 experienced colorists rating is based on observation of the dyed hosiery, and is as follows:

*4 Excel1ent=0palescent smooth silky high sheen, the preferred Glace Look". *4 Good (A) =Opalescent silky sheen "Glace Look present but slightly subdued. *4 Good (B) =An opalescent high sheen with the preferred "Glace Look" but some sparkle present. *5 Excel1ent=High shimmer or point sparkle, the preferred Scintilla Look". *5 Good (A) =Luminescent point sparkle "Scintilla Look present but slightly subdued. *5 Good (B) =High shimmer or point sparkle, a heavy Scintilla Look" approaching the upper acceptable limit before it becomes too garish.

After preboarding, the luster properties of these hosiery are 70 determined on the undyed white yarns and compared with hosiery prepared having different cross-sectional modifications as controlled. The method for obtaining luster values listed in table 1 are given in the description herein. The in-- Table 2 illustrates the elastic properties for various hosiery made from different types of cross section. Bifilament yarns containing 0.3 percent TiO, and 2 percent TiO exhibit similar elastic properties to that illustrated by the bright yarns.

Boarded stockings were dyed in a conventional manner, dried by a tray method, and placed in an lnstron tester to evaluate the stretch properties of the hosiery. The hosiery were pretensioned at 1 percent of the total lnstron loading which was grams minimum and 2,000 grams maximum. The

terpretation as to the quality of the appearance is based on 7 pretensioning force was between 1 and 20 gran s, depending 2 ill upon the degree of s t re t ch ili he K555515555 tested and the superiority of hosiery made from bifilament false-twist in work loads required to elongate the hosiery to 25 percent. The Inof recovery may be observed. stron employed was equipped with a G-61-3C air-operated Hosiery made from bifilament false-twist, after six cycles, clamp having 2-inch rubber faces which were clamped with 60 show a l2-gram stress force at 3 percent elongation as compounds pressure. The cross head and gage length were the pared with hosiery from round filament false-twist yarn of 2 same and a 25 percent elongation was achieved in seconds. grams and triangular cross section false-twist yarn of 1 gram. There were 2 inches of hosiery separating the clamped jaws in At 5 percent elongation the hosiery made from bifilament a lengthwise test, and 1 inch of hosiery separating the clamped false-twist yarns; round filament false-twist yarn and bicomjaws in a transverse test. ponent round cross sectionyarn and tri ang lar cross section TABLE 2.FORCE IN GRAMS FOR HOSIERY EXTENDED LENGTHWISE AT THE INDICATED ELONGATIONS 1 Percent Ankle elongation, percent Percent Knee elongation, percent Example I work of work of Number Test hosiery from the lndicated yarn types recovery 2 3 5 10 25 recovery 2 3 5 10 25 9 Bifil false-twist 1 59. 3 29 50 145 58. 3 1s 22 32 75 Standard knit stretch hosiery 3 6 64. 2 12 18 36 136 63. 2 8 12 23 70 11 Round filament false-twist 1 43.7 14 20 40 113 54.0 12 17 30 7s Standard knit stretch hosiery 3 6 50. 5 2 5 22 103 56. 4 3 7 19 73 13 Bicomponent round cross section l 44. 6 18 25 50 200 53. 2 18 25 45 142 Standard knit stretch hosiery 3 6 48. 2 4 12 32 195 58. 1 7 12 136 7A Triangular cross section false-twist 6 52.0 1 5 25 105 47.1 1 3 12 5o 3 Bifilament cross section 1 44. 4 300 400 800 2, 300 45. 0 300 500 850 1, 800 1 Standard knit hosiery nylon 6 3 6 59. 0 60 70 300 2, 100 60. 4 50 350 l, 600 6 Round cross section 1 39. 0 400 650 1, 300 3, 600 41. 0 300 500 950 2, 360

Standard knit hosiery nylon 6 3 6 56. 0 50 400 3, 300 52. 5 50 450 2, 100 14 Bifilament cross section 1 40. 6 450 800 2, 000 6,500 45. 7 200 350 650 Mesh knit ny1on 6 6 57. 5 10 60 500 6, 200 61. 2 10 20 300 T Triangular cross section l 38. 7 600 1, 000 2, 200 6, 250 41. 1 200 320 700 Mesh knit -nylon 6,6 6 58. 5 400 5, 800 58. 8 200 1 The values in the table are all expressed in grams with the exception 0! work of recoyery.

2 Work of recovery is the ratio of recoverable work to the total work required to strain a fiber or fabric a specified amount under a given program of strain rate. In this case, it was determined at 25% elongation, 15 seconds forward cycle, 15 seconds return and was calculated according to AS'IM D-1774-64, ASIM Standard (1964) part 25.

3 Standard knit, plain or jersey stitch.

4 Load too small to show on chart.

Mesh knit=tuck stitch.

6 Too small to read on Instron on 10,000 gram load scale.

Referring to results shown in table 2 above, it can be noted false-twist yarn have stress forces in grams respectively of 18, that hosiery prepared by bifilament false-twist and the bifila- 4O 5, l2 and 5. ment nontextured yarns have the highest work of recovery of Table 3 illustrates the stress forces of hosiery prepared from all yarns tested for equivalent examples and the improvement yarns having various cross sections which are subjected to in terms of work of recovery is the greatest after six cycles. elongations in the transverse direction. Most important, stress loads in the ankle and knee region are igbiggfggg g y f b bifil t f l t i t yams Significantly higher for blfilamem Y at 3 and 5 P f (example 9) have a stress force of 5 grams at 3 percent elongaelongation as compared with round triangular or even blcom't )tion in the transverse direction after six cycles whereas round P y 'false-twist yarns (example 1 l) have 20 percent of this value,

It should be emphasized that it is smgularly un I0 find and triangular cross section false-twist yarns have 40 percent hosiery combining exceptional optieal properties and with the of this value. Bicomponent round cross section yarn hosiery further advantage ofelastic propernes which remain relatively (example 13) have no force at 3 percent elongation and only l l' 3f WW5? F g- 43 percent of the 7-grams value exhibited by the bifilament TABLE 3.HOSIERY PHYSICAL PROPERTIES-TRANSVERSE Below welt-thick Ankle elongation, area elongation, percent (grams) percent (grams) Test hosiery from indicated No. of Ex. No. yarn types cycles 3 5 10 25 3 5 10 25 9 Bifil false-twist 1 6 5 7 12 50 5 7 15 11-. Round false-twist 1 6 1 3 5 26 2 7 50 13-. Bicomponent 6 3 6 15 3 5 10 25 7A1 Triangular cross section false-twist 6 2 5 40 125 3 7 3... Bilfil cross section plain knit 2 r. 6 5 10 50 190 5 550 6..- Round cross section plain knit 2 0 4 10 470 5 80 460 14.- Bilfil cross section mesh knit 6 5 10 40 380 10 10 30 570 7 Triangular cross section mesh k 6 5 10 35 5 8 25 270 1 Plain or jersey knit hosiery. 2 Plain or jersey knit; no false-twist.

In table 2, hosiery made from the bifilament false-twist yarn cross section yarn hosiery, at 5 percent elongation. Thus, the of example 9 has a work of recovery of 64.2 percent which is 7 bifilament false-twist yarn has superior stress-forces compared 128 percent greater than that of the hosiery made from the with other cross-sectional yarns. Moreover, hosiery made round cross section false-twist yarn of example 11, 121 per-- from bifilament plain knit having no false-twist (example 3) cent greater than hosiery made from triangular cross section have much more comfortable extension force at 10 percent, false-twist yarn, and 133 percent greater than hosiery made 15 percent, 20 percent, and 24 percent than that obtained for from bicomponent standard knit stretch hosiery. The values 75 round cross section yarn indicating the inherently greater are somewhat less pronounced ip the knee section but still the elasticity for the biiilament plain knit hosiery.

" ITiBTe Inmate;ati'are'sgimaa pai-ib'f'i'lieiaric pro perties of the hosiery. In this case, the hosiery was extended to 25 percent elongation and allowed to return to 12% percent elongation and the forces in grams were obtained at this point by reading from the chart. This value is designated as a power of recovery;

3, 8, 9, and exhibited approximately the same sheerness as at b sriaqi .0 dan euqan cross Section msnefllemaa TABLE 4.POWER OF RECOVERY"EXTENSION TO 25% ELBNGATION WITH MEASURE- MENT OF LOAD 0N RETURN TO 12%% ELONGATION Transverse or width Lengthwise of hosiery direction of hosiery Ex. Hosiery made from the Number No. indicated yarns of cycles Ankle 1 Knee 1 Thigh l Ankle 1 Knee 1 Thigh 1 9 Bifil false-twist 2 6 25 7 10 8 7 11- Round cross section false-twist L--- 6 8 8 5 3. 5 3 3 l3 Bicomponent round cross section 6 7 12 3. 5 5 5 7A.... Triangular cross section false twist 6 12 7 3 Bifil 1 6 150 125 100 40 50 6 Round 2 6 150 60 50 30 20 10 Bifil mesh knit 6 250 175 250 35 26 26 7 Triangular mesh knit sparkle yarn 6 200 100 125 20 12 f Force ingrams after extension to 25% elongation and return to 12%% elongation is designated the "power 0 recovery 2 Plain knit or jersey knit hosiery. a No data.

Hosiery made from false-twist bifilament yarn (example 9) have a lengthwise stress force at the ankle section of 25 grams which is 310 percent greater than round cross section yarn (example ll), 210 percent greater than triangular cross section yarn (example 7A), and 350 percent greater than bicomponent round cross section stretch yarn. Moreover, the power of recovery of hosiery made from false-twist bifilament yarns, when measured in a transverse direction in the ankle region after six cycles, is 10 grams. This is 280 percent greater than hosiery made from false-twist round cross section and triangular cross section yarns.

The bifilament nontextured yarn converted to hosiery, as shown in table 4, has a power of recovery in the knee section after six cycles of 125 grams which is 210 percent greater than round cross section yarn in equivalent hosiery construction.

Table 5 illustrates the maximum elongation of hosiery made from stretch yarns at various load points. As can be observed in table 5, hosiery made from bifilament false-twist stretch yarns (example 9) were superior to hosiery made from round cross section false-twist and round bicomponent yarns. After a single cycle, the bifilament false-twist yarns were substantially superior to bicomponent round cross section stretch yarns as to total elongations.

perties provide sheerness and simultaneous good-wearing quality of the hosiery.

Bifilament hosiery made from polyhexamethylene adipamide showed approximately equivalent improvement in physical properties and in luster effects as that already described for polycaproamide yarns when compared with the round cross section yarns made in identical conditions except as to spinneret employed. The spinning temperature was 280 C. in order to produce a satisfactory bifilament from polyhexamethylene adipamide.

EXAMPLES 17-20 Bifilament cross section false-twist 20/1 denier (example l7) round cross section false-twist 20/1 denier (example 18); round cross section false-twist 15/l denier (example 19); and

triangular or trilobal cross section false-twist 20/1 denier (example 20) were prepared in a similar manner to that described fwaam r ft v kni ed into h s e ar ed e iq sd 1 This value was obtained in the test procedure similar to that for the yield point in yarns Where a straight line is taken along initial load line, then a similar straight line is drawn at maximum loading or stress to bisect the first line drawn and then a straight line from this intercept point is drawn to intercept with the stress-strain line drawn by the Instron.

This intercept point is called the Yield Point.

as described in examples l-l4. These hosiery were then evaluated by a panel jury of 22 women normally wearing hosiery sizes 8% through 11. These hosiery were finished to an average length of 35 inches and were equivalent to that of medium size range of stretch hosiery. The panel rated the bifilament yarn hosiery from good to excellent in terms of comfort of fit, appearance and sagging or tightness characteristics, and wearing qualities such as pick and run resistance. This extended over the entire range of ladies sizes tested. Their ratings appear in table 6.

In table 6, it can be observed that the hosiery prepared from rn ade from round cross section a standard form bifilament false-twist yarn (example l7) was rated exceptional AS To ONE SIZE D TO MEDIUM L CHARACTERISTICS OF HOSIERY MADE ENGTH AND 9 FOOT SIZE Appearance sagging Pick and run characteristics of resistance wear Comfort or fit tightness lite Example N 17 18 19 20 17 18 19 20 17 18 19 20 Size range:

IOV -ll 4.33 3.0 2.0 1.66 4.66 2.66 2.0 1.66 2 2.3 2.3 Ql-IO... 4.75 3.0 2.75 1.5 4.4 2.75 3.2 2.0 4.75 3.4 3.75 5 8 9 4.3 2.0 4 2.0 4.66 3.5 2.5 2.5 5 31 4.33 2.5 Overall rating. 4.45 2.8 2.9 1.67 4.55 2.9 3.0 2.0 4.83 2.0 3.50 3.0 Zero tensionlength after boarding heel to welt avg., in 19. 65 21.0 15.1 16.6

NOTE: Examples 17, 18, 19 and 20 con to a length of about 35 inches; Exam twist 20/1 denier; Example twist 20/1 denier.

Comfort or fit: 5=Excellent; 4= Good; 3=Fai Appearance, sagging or tightness characteristi Too tight to consider wearing.

Wearing qualities, run and pick resistance: (2) =Rnn after 2 wea ple 17-Bifilament cross se Round cross section falseat the 10% to 1 1 size range and less outstanding at 8 /2 to 9 size range but still showed up significantly superior to all other yarn types rated by the panel jury. It is exceptional where there is unity of test values and test ratings because of characteristic divergence of individual responses by women jurors in prior tests of this type.

It can be noted also that the overall rating for the bifilament yarns was quite superior to both denier and denier round cross section false-twist yarn hosiery and considerably superior to the triangular or trilobal cross section false-twist yarn hosiery. The explanation for the numerical values for comfort or fit; appearance; sagging or tightness characteristics, and the wear qualities such as run and pick resistance is given at the bottom of table 6. In over 200 wearings, the bifilament hosiery exhibited only one pair of hose which r s ei ren..Ih m9. x sptisnelwe r if i attributed. as

tained 2,100 courses from heel to the welt ction false-twist 20/1 denier; Example 18- twist 15/1 denier; Example 20-lriangular or typically in use, the hosiery would be extended Round cross section falsetrilobal cross section falser; 2=Poor; 1=Too uncomfortable to consider wearing. cs: (5) =Excellcnt, completely sag-free; (4) Slight sag; (3) =Tight; (2) Heavy sag; (l)

runs or picks; (4) =Slight pick, no runs; (3) =3 or more wearings without runs;

keeping the garment in place on the wearer.

Similar panty hose were prepared from round cross section 20/1 yarn in the leg section and 12 denier false-twist yarn in the waist section. Additionally, a like structure was prepared from triangular cross section false-twist yarn.

in trial wear tests, after 20 wearings, the panty hose made from bifilament yarn showed no evidence of sagging, nor did it develop runs in the hosiery section. Both the triangular cross section and the round cross section hosiery developed runs in the leg section and sagged even after a few wearings.

However, there still was a problem that the elastic band made of Spandex provided insufficient force to maintain the hosiery with completely satisfactory tension. For instance, after changing from high heels to flat wear, sagging of the hosiery was slightly noticeable. 1

Bifilament yarns made up into panty hose had the following measurements:

Hosiery section 1 Torso or panty section bifil F.'I.

No. of Bearded Type No. of Length, Total courses length, in. yarn courses DcnJfil. in. courses 5 Small size 2, 300 20 20/1 bifil 500 40/12 12. 5 2, 500 Medium size 2, 700 23 .do 520 40/12 13 2,700 Large size 2,900 24% .....do 620 40/12 15% 2,900

1 The values shown in 2 The length shown i straighten the hose.

This section is from the top or the hosier elude from the heel to the shadow welt. ncludes from the heel to shadow welt and is measured with only sufficient tension to y shadow welt to the elastic band at the top of the panty section.

4 Stretched to normal wearing length 'lotalcourse from heel t to the idealized geometry of the cross-sectional configuration of the bifilament yarns of this invention.

EXAMPLE 21 While the problem of sagging in ladies hosiery has been discussed, this problem is at a significantly reduced level as compared with the sagging in panty hose. In this case, the sagging characteristics cannot be corrected by increasing the tension on the ladies hosiery by refastening of the hosiery, since they are permanently fastened to the panty section. Thus, in a short time, sagging which has been discussed in the round and triangular cross section false-twist yarn, and particularly in the bicornponent round cross section stretch hosiery, is a troublesome and annoying problem.

Panty hose comprised of a torso section having attached leg portions were prepared on conventional knitting equipment by constructing the leg or hose portions from semidull 20/1 denier bifilament having 30 twists per inch and then constructing the panty section from 40/ 12 denier semidull bifilament multifilament yarn which was false-twisted 120 turns per inch.

After knitting; the tubular section for the enlarged tubular section was slit and sewn to size with suitable insert in the center section. A conventional elastic band containing Spandex was inserted at the top of the panty section to assist in o the elastic band at the top of the torso section.

EXAMPLE 22 in a second trial both the torso section and leg sections were made from 20/6 bifilament semidull false-twist yarn. A power not composed of 20/1 denier bifilament yarn false-twisted to 31 turns/inch and knitted with jersey stitch was placed over the torso or waist section. The power net was sewn at 2-inch intervals with a single stitch to hold it firmly in place over the multifilament 20/6 denier yarn waist section. The 2-inch interval provided adequate space for the bifilament yarn to act as a grid structure and provided for adequate elasticity to hold the hosiery firmly in place. Additionally, the structure possesses sufficient retractive force to function as a girdle to provide some form fitting assistance.

Table 7 lists the stress forces possessed by power nets knitted using different types of false-twisted yarns. These values may be compared with commercial Spandex segmented polymers at 25, 40, 50, 60, and percent elongation. As can be noted, the bifilament yarns of this invention in power nets have greater stress force than does Spandex at 50 and 70 percent elongations and are vastly superior to rubber in terms of stress forces at the indicated elongations.

The power of recovery of false-twist, bifilarnent hosiery after an extension of 25 percent andl return to 11% percent elongation in the ankle section is 0.0042 grams/denier as compared with 0.00135 grams/denier for hosiery of round cross bifilament yarn for achieving at given points different section false-twist yarn. degrees of stress forces;

By review of table 2, it can be observed that bifilament 4. The direction of the wales may be altered to maximize yarns retain more than 93 percent of their stress force after 6 tre for es in the area where maximum figure control is cycles of 25 percent elongation, which is comparable to that 5 desired; and obtained f pe 5- Thesesa inmate Wsevsmianp Y TABLE 7.-POWER IN GRAMS/DENIER IN THE LENGTHWISE OR WALE DIRECTION OF POWER NET FOR TYPES OF FALSE-TWIST YARN Percent elongation Ex. No. 26 40 50 60 70 75 80 22"... Bifilament false-twist denier 0.0285 0.0423 0.0473 0.0502 0.0615 0.0675 Past 6% stress point 23.... Round false-twist, 20 denier 0.023 0.0285 0. 0333 0.0388 0.0485 Past 6 stress...

24 Bicomponent round 20 denier hosiery- Past 6 stress Past yield point (see Table 5) 25.-- Commercial spandex segmental polymer 0.030- 0.038- 0. 04 0. 047 0. 050

26--- 'R ubber 0.004.. 0 008 0 009 0 0095 27-.- Bifilaments transverse or course direction- 0.013-

28"-" Round transverse or course direction 0.0072

1 After 6 cycles of elongation.

F The 6 yield point is thatpoint at which the stress strain curve deviates more than 6 from the best fit for a straight line drawn along the manor initial portion of the stress-strain curve slrnllar to that for determination of the yield point (see Table 6.) The yield point occurred at approximately angle deviation from the same line.

3 The values cited for commercial Spandex were the highest of 4 commercial varieties tested. Several commercial varieties had stress values at 2 of that of the commercial Spandex cited. The values for Spandex and rubber were determined on the individual yarns, whereas the values for Examples 22, 23, and 24 were determined on a power not.

4 Cross section, false-twisted 20 denier. 7 H w s in table 7, it can be noted that the bifilament yarn in a transa substantial prior art problem of yellowing which is verse or course direction has stress force values in terms of characteristic of the aromatic segments in Spandex-type grams per denier approximately one-half of that obtained in yarns. the lengthwise or wale direction. Thus, this is a particular ad- 30 The enhanced cover which is characteristic of the monofilavantage, since the directional force or stress forces for figure ment yarn in semidull bifil yarns may be superimposed on a control can be achieved by placing the power net with the 20-denier/6 filament to provide adequate and satisfactory wales in the direction desired to achieve the greatest force for cover in the waist section of panty hose. it is equivalent to that form control. obtained from denier/l2 multifilament yarn, and, addi- From the foregoing detailed description, the following ob- 35 tionally has the advantage of the power net structure superimservations can be made: posed thereon. l. A fully satisfactory one-size stretch hose of exceptional we claim.

f' comfort qualmes and unusual luster l. A knitted structure comprised of successive courses and 'F 9 produced- These hose may be used m wales of false-twisted polyamide bifilament yarns of 7 to 30 wll-h a body P to Pmdlwe a P hose deniers composed of prominent lobes having an intercept e fl m d freedom q 88 98 angle ranging from 10 to 54 circular peripheral surfaces con- A panty hose having Superimposed thereon in the waist nected together by concave side portions of uniform symsection a power net which achieves both a reduction in merry to f rm a fl i h cross Section configuration, id the sagging problem in he ankle Section Of the h i ry, lobes having surfaces of curvature no greater than the surface and achieves good figure control as-a panty hose girdle; curvature of said concave side portions, said yarns being 3. It should be clear to those skilled in the art that numerous li d at yam ros ing oints so that a lobe portion of one c m n i n of h above n be hi F n n yarn rests against a concave side portion of an adjacent yarn high sheen, high luster hose can be used in combination whereby twist is entrapped between loop sections forming the with a semidull panty section. The power net structure course and wale construction network of the knitted structure can be made using various combinations of deniers of the thereby enhancing the stretch characteristics of said structure. 

1. A knitted structure comprised of successive courses and wales of false-twisted polyamide bifilament yarns of 7 to 30 deniers composed of prominent lobes having an intercept angle ranging from 10* to 54* circular peripheral surfaces connected together by concave side portions of uniform symmetry to form a figureeight cross section configuration, said lobes having surfaces of curvature no greater than the surface curvature of said concave side portions, said yarns being aligned at yarn crossing points so that a lobe portion of one yarn rests against a concave side portion of an adjacent yarn whereby twist is entrapped between loop sections forming the course and wale construction network of the knitted structure thereby enhancing the stretch characteristics of said structure. 